1. Field of the Invention
The present invention relates to ignition systems. More particularly, the present invention relates to ignition systems which produce constant energy ignition pulses independent of power supply variation.
2. Description of the Prior Art
U.S. Pat. No. 4,019,484 discloses an ignition system for an internal combustion engine having a dwell time interval equal in duration to the low state of a first comparator. The duration of the low state has a duration equal to pulses outputted by a reference time generator. The reference time generator is a second comparator that produces an output pulse in response to the falling edge of each pulse produced by the first comparator which has a constant duration in a first embodiment and a duration which varies as a function of supply voltage in a second embodiment. The operation of this system is intended for use with a pick up coil which produces an AC signal. The operation of the comparators is based upon level comparison including a signal derived from the AC signal.
Other ignition systems are known which electronically control the dwell of the energy storage cycle to produce constant energy ignition pulses. See. U.S. Pat. Nos. 3,831,571, 3,937,193, 3,943,896, 4,018,202, 4,121,556, 4,212,280 and 4,237,835.